private function get_devicenames()
 {
     if(isset($_GET['filter'])){
         $mapfilter = $this->mapfilter();
         $installfilter = $this->installfilter();
         $sql = "SELECT distinct Name, Town_id, District from Devices where $mapfilter and $installfilter order by Name limit 1000";
     }
     else{
         $sql = "SELECT distinct Name from Devices order by Name limit 1000";
     }

     $this->run_query($sql);
 }